Does Lawn Fertilizer Kill Weeds?

Lawn fertilizer helps in a lot of ways when it comes to gardening. As a fertilizer, its main job is to feed and help maintain a healthy, fast growing lawn. But does lawn fertilizer kill weeds?

Lawn fertilizer can actually do quite the opposite and promote weed growth due the benefits and nutrients it is providing the rest of your lawn. There are, however, options available if you are more interested in removing the weeds and fertilizing at the same time. 

What is a Lawn Fertilizer?

Lawn fertilizers can be made from either man made material or organic material. They can come in either granular or liquid format, and can be distributed on the lawn in a variety of different ways. 

Liquid Lawn Fertilizers

Liquid lawn fertilizers are often stored in a spray bottle or a bottle which can be attached to a garden hose for easy distribution. They are best used in small yards due to the limited amount that can be bought in one bottle. These fertilizers can be mixed with additional gardening chemicals and can be added to herbicide to remove weeds. 

Liquid lawn fertilizers have many benefits, such as having pet-safe options, which should be considered when deciding which type of fertilizer suits your needs best. 

Granular Lawn Fertilizers

Granular lawn fertilizers are the more popular type of fertilizer available. This is because they’re the tried and tested method. They work best in large areas as there are many ways that this fertilizer can be spread, including the use of a hydroseeding cannon, to cover large areas.  The main risks associated with granular lawn fertilizers involve overfeeding or underfeeding certain areas of the lawn, and the risk of animals eating or destroying the granulas before they are absorbed by the lawn. Granular lawn fertilizers can also go bad if stored incorrectly. 

What’s the Best Fertilizer for My Lawn?

The best lawn fertilizer for your lawn depends on the type of grass you have and the general health of the soil it is planted in. There are many different types of grass which each require different nutrients to keep them strong and healthy. In addition to this, the type of soil you have can play a large part in what nutrients  your grass is receiving. The best way to choose an effective fertilizer is to consider the type of grass you have, the type of soil you have, and conduct a pH test on your soil to determine which nutrients are needed for your lawn. 

Choosing between liquid and granular fertilizer is also a decision that can be made depending on your own circumstances. Liquid fertilizer is best for smaller areas, whilst granular is best for larger areas. Make sure to read the instructions and requirements for both of these fertilizer types before choosing, as one might be more beneficial to your lawn than the other. 

How does Lawn Fertilizer Work? 

Lawn fertilizer works by delivering necessary nutrients to the lawn which may otherwise be hard to obtain or the lawn may be deficient in. This helps the grass grow faster, thicker and healthier, and allows it to fight off potential disease quicker. Lawn fertilizer should have the acronym NPK on its packaging, along with three numbers. The NPK acronym stands for Nitrogen (N), Phosphorus (P) and Potassium (K). The three numbers listed next to this acronym detail the percentage of the nutrient included in the compound. So, for instance, an NPK of 30-20-20 would mean 30% is nitrogen, 20% is phosphorus and 20% is potassium. These percentages help determine which fertilizer compound is best for your lawn, and can help you decide which compound combination is best suited for your grass and the goals that you have for your lawn. 

weeds growing on a grassy lawn

Benefits of Lawn Fertilizer

Using lawn fertilizer has a variety of benefits. Not only does it help your lawn retain its healthy rich color during times of the year when it fades, it also helps bolster your lawn’s growth, health and density. A strong, dense lawn is better at resisting disease, fungi such as lawn rust and even certain types of weeds and moss. It is often more of a preventative measure than one that causes direct action against these invasive diseases and afflictions. 

How Often Should I Fertilize My Lawn?

You should fertilize your lawn when it is going to require the additional nutrients to keep it alive and healthy. This means it is usually fertilized after summer, but before the first cold snap of winter. People often choose to fertilize their lawns in September or early October. Some people opt to put their fertilizer down in the spring before drought or high heat settles in for the summer. Either way, the lawn is fertilized to enable it to survive harsh weather conditions that may be coming up or may have just finished. Lawn fertilizer shouldn’t be applied before heavy rain due to the dilution it can cause. However, it is safe to scatter fertilizer before or after a gentle rain, often found during springtime. 

Fertilizing your lawn too often or using the incorrect formula could result in fertilizer burns in your grass. This can be avoided by reading any instructions for diluting on the packaging, and only fertilizing when necessary. 

Does Lawn Fertilizer Kill Weeds?

As discussed, lawn fertilizer exists as a way of bolstering and improving the health of the lawn and soil which it grows in. Unfortunately, this can also do the same for any weeds hiding amongst the lawn, especially if they rely on the same nutrients as the lawn does. Lawn fertilizer applications can see an increase in dandelions, bindweed, or any weeds that look like grass which could be hiding in plain sight. It depends entirely on the weed and the nutrients that it needs to sustain itself, however. Some weeds will be killed or prevented from going in particularly nitrogen-rich soil. It’s best to be aware that lawn fertilizer isn’t designed to kill weeds, however, and that you may need to consider other options for weed removal

Does Lawn Fertilizer Kill Mushrooms?

Whilst lawn fertilizer may be ineffective against some weeds, it can prove effective against fungus in the lawn. Nitrogen-rich soil is likely to kill mushrooms and prevent them from growing. There are additional ways to get rid of mushrooms in your lawn, if your lawn fertilizer doesn’t seem to work. Fast release lawn fertilizer, particularly liquid lawn fertilizer, is best for removing mushrooms as they’re likely to be affected more by the nitrogen as opposed to slow-release fertilizer. 

How Can I Kill Weeds?

Weeds can be killed in a variety of different ways. Some people swear by homemade methods, but the most effective and tried method of removing weeds is one that has been proven to be additionally beneficial to the grass. Weed and feed is a solution which kills weeds whilst fertilizing and feeding the grass. Weed and feed should only be applied in certain conditions, so make sure you read the instructions before use. It is designed to target weeds whilst feeding the grass around them to bolster the lawn’s health. This is achieved by adding a mixture of herbicide in with the nutritional ingredients that support the lawn’s growth. 

How does Weed and Feed Work?

Weed and feed uses herbicides which are generally tolerated by grass in order to kill weeds that are present in the lawn. It is absorbed by the weed’s leaves which helps kill them. Whilst doing this, the formula provides your lawn with much-needed minerals, particularly nitrogen, to promote healthy and strong growth.

Will Weed and Feed Kill My Lawn?

Weed and feed should not kill your lawn provided the instructions are followed and that your lawn is accepting of the additional minerals that will be added to it. It’s always worth remembering that if your lawn has an excess of a certain chemical, it can throw off the pH balance of your soil and lead to plant death. If your lawn is already high in nitrogen, adding a solution that is high in nitrogen atop of it may lead to trouble. In addition to this, too much weed and feed has the potential to burn or damage your lawn in other ways. This could be due to overuse or too much solution being added at any one time. Make sure to read the instructions carefully before applying weed and feed to your lawn. 

Pre and Post-Emergent Weed and Feed

There are two different types of weed and feed available, pre-emergent and post-emergent. These two titles are for differentiating the manner in which you’ll be using it to remove weeds. Pre-emergent weed and feed is applied before weeds have begun to grow, as a preventative measure. On the other hand, post-emergent weed and feed is applied after weeds have appeared, in an effort to remove them from the garden after they have grown. 

Where do Weeds Come From?

Weeds can develop based on the conditions which they are presented with. Weeds, like other plants, grow from fertilized seeds. These seeds can be spread in a variety of different ways, such as through the air, through animals, and by clinging onto our clothes or our pets. Weeds are incredibly versatile and can grow nearly everywhere, and due to this robust nature, they can be very hard to kill. The best way to kill weeds completely is by ensuring their roots are unable to grow or regenerate, which is why using a herbicide that is absorbed by the leaves and body of the plant is the best way to kill them off.  

Fungi, for instance, may not be considered a weed but it is an unwanted addition to your garden. Fungi grows best in dark, damp, humid conditions which can be brought about in various ways. Fungi is most likely to grow in lawns which may suffer with thatch, standing water, or grass bubbles. It can also begin to form if debris is covering the lawn, such as pine needles

Can Lawn Fertilizer Damage a Lawn?

There is such a thing as too much of a good thing! Lawn fertilizer absolutely has the ability to harm or kill grass, depending on the circumstances in which it is applied. Your lawn’s chemical makeup will leave it predisposed to requiring certain nutrients and not needing other ones. It’s important to know which nutrients your lawn needs, which ones it doesn’t, and how much of each nutrient it needs before choosing to fertilize. Adding too much of one nutrient could not only kill weeds, but kill your grass along with it. This is because it can make the soil inhospitable, and prevent growth due to its pH levels. It is possible to change pH levels over time, so it is important to keep an eye on them. In addition to this, fertilizer burns can affect the lawn if too much is applied in one area. It’s always ironic for something designed to help make your lawn look better to end up damaging it and leaving an unsightly patch in the center!
When purchasing lawn fertilizer, make sure you know the NPK levels you need and the percentages that are right for your lawn. If not, perhaps speak to an expert to help guide you to the best solution for you. The wrong fertilizer can cause more trouble than it’s worth in the long run. 

Final Thoughts

Lawn fertilizer has many benefits, but the ability to kill weeds should not be considered one of them. If your lawn fertilizer is killing weeds without the addition of herbicide, one should consider changing for the sake of your grass, as it could be affecting the soil and making it inhospitable. There are more effective ways to kill weeds, such as weed and feed, which is a compound designed with both bolstering grass and destroying weeds in mind. Always be aware of what chemicals and minerals you are using in your lawn, as different lawns have different requirements and needs. If you’re unsure, always make sure to consult a specialist before going ahead with any new products or making any changes to your fertilization routine. 

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